* not completed

. Which mechanism for the appearance of a new gene in a species' genome could also explain different phylogenetic tree topologies when using different genes?

Retrotransposition correct incorrect

Neofunctionalization after gene duplication correct incorrect

Exon shuffling correct incorrect

Horizontal gene transfer correct incorrect

Mutations in noncoding DNA leading to de novo genes correct incorrect

* not completed

. There are 1,200 functional olfactory receptor genes in the mouse genome and only 550 in the human genome. Which of the following is a possible reason?

A whole genome duplication of the mouse genome occurred in the recent past. correct incorrect

Primate genomes are an order of magnitude smaller than other mammalian genomes. correct incorrect

Many olfactory genes were duplicated in the mouse lineage. correct incorrect

Genes that are rarely used can degenerate because of reduced selective pressure. correct incorrect

All of the above correct incorrect

* not completed

. Which is an example of subfunctionalization of a gene duplicate?

A duplicate of a metabolic gene evolves to work as an antifreeze protein in an Arctic fish. correct incorrect

Duplication of hemoglobin genes allows different versions to be expressed where they perform most efficiently. correct incorrect

Retrotransposition of the Alu elements into many positions in the genome correct incorrect

A gene is duplicated to a new position in the genome, but its regulatory elements are missing, so it is never expressed. correct incorrect

Gene duplication leads to new combinations of existing exons, as in the jingwei locus. correct incorrect

* not completed

. A researcher studying a member of the Conus genus of cone snails discovers that there are many dozens of slightly different variants of venom proteins coded by closely related genes. What is the most likely explanation for this great variation? [Hint: The compounds likely diversified in a similar way as the multiple globin proteins in mammals did.]

Multiple gene duplication events have led to the production of a paralogous multigene family. correct incorrect

Hybridization between two snail species has left the offspring with multiple orthologous genes. correct incorrect

Duplicated genes underwent incomplete gene conversion, leading to many errors in sequence. correct incorrect

Concerted evolution resulted in the production of many venom genes, scattered throughout the genome. correct incorrect

The last common ancestor of all cone snails had a diverse set of venom genes that have been inherited by all cone snails. correct incorrect

* not completed

. Why do pseudogenes evolve so much more quickly than other genes?

Pseudogenes are processed more quickly because there are no enzymes present to check for replication errors. correct incorrect

Directional selection causes rapid change in their sequence. correct incorrect

High rates of recombination in pseudogenes are often subject to unequal crossing over. correct incorrect

Transposable elements target pseudogenes as a site of insertion. correct incorrect

They are not subject to purifying selection because mutations have no functional consequence. correct incorrect

* not completed

. Mutations at the third position of the codon are more likely to _______ than mutations at the first or second position.

be selectively neutral correct incorrect

be fixed by genetic drift correct incorrect

be synonymous correct incorrect

result in gene product with the similar properties as the original gene correct incorrect

All of the above correct incorrect

* not completed

. What is codon bias?

A measure of the departure from equality of the frequency of synonymous codons for a given amino acid correct incorrect

A measure of the departure of GC content from 50 percent correct incorrect

A measure of the size of a gene correct incorrect

The tendency of natural selection to favor novel stop codons correct incorrect

The difference between upstream and downstream regulatory sites correct incorrect

* not completed

. The existence of ultraconserved elements in the human genome that do not code for protein provides evidence that

only 1.5 percent of the human genome codes for protein. correct incorrect

many genomic regions outside of protein-coding genes are functional. correct incorrect

only the transcriptome of an organism is affected by natural selection. correct incorrect

the deletion of genes with high dispensability will not reduce fitness significantly. correct incorrect

many mRNAs may be encoded by a single gene. correct incorrect

* not completed

. What is the major benefit to organizing genes into operons?

Efficiency in transcription and translation correct incorrect

Separating genes under strong selection to reduce the impact of insertions of transposable elements correct incorrect

Chromosome rearrangements will be less likely to affect selective pressures. correct incorrect

Introns are able to be spliced in different ways, producing multiple gene products at a single locus. correct incorrect

All of the above correct incorrect

* not completed

. Alternative splicing and overlapping genes are ways that organisms can

reduce the fitness impact of parasitic DNA like transposable elements. correct incorrect

ensure that functionally related genes evolve together. correct incorrect

increase the range of protein product they produce without expanding genome size. correct incorrect

produce gene duplicates with novel function. correct incorrect

regulate gene expression at the level of protein translation. correct incorrect

* not completed

. Which event will not alter an organism's karyotype?

Allopolyploidy correct incorrect

Chromosome fission correct incorrect

Chromosome fusion correct incorrect

Sequence inversion correct incorrect

Aneuploidy caused by nondisjunction of chromosomes during meiosis correct incorrect

* not completed

. Which explanation is the least likely reason for why a chromosome inversion increases in frequency in a population?

The inversion could alter gene expression in a beneficial way and increase in frequency by positive selection. correct incorrect

Inversions subject to meiotic drive will be present in a greater proportion of gametes and increase in frequency. correct incorrect

Inversions can proliferate by catalyzing their own formation, thus increasing in frequency. correct incorrect

Inversions can prevent recombination, keeping together favorable combinations of alleles; positive selection will increase its frequency. correct incorrect

Inversions can increase in frequency by genetic drift. correct incorrect

* not completed

. What is the best explanation for the observation that eukaryotes that seem superficially simple can have much larger genomes (in terms of mass or number of base pairs) than organisms that have complex anatomy, structure, or behavior?

Alternative splicing and overlapping genes are rampant among eukaryotes. correct incorrect

Some organisms have a tremendous amount of noncoding DNA, like repetitive sequences. correct incorrect

Simpler organisms require more chemical defenses against enemies. correct incorrect

Animals with simple body plans are adapted for rapid DNA replication. correct incorrect

DNA in the mitochondria and chloroplasts are not counted in these measurements of genome size. correct incorrect

* not completed

. In which location in the genome are transposable elements least likely to experience strong selection?

An exon of a protein coding gene correct incorrect

Between a gene's promoter and its coding region correct incorrect

A noncoding area of the genome that experiences little recombination correct incorrect

A noncoding region that experiences very high recombination correct incorrect

A protein coding gene's intron correct incorrect

* not completed

. The genomes of viruses are very small because

small genomes are an adaptation that allows for faster copying. correct incorrect

many viruses utilize the molecular machinery of their host cells. correct incorrect

of codon bias. correct incorrect

viruses have evolved only recently. correct incorrect

Both a and b correct incorrect